I'm filling out my advance directives for medical care in case I'm incapacitated. I have zero perspective on the potential treatments at various stages of incapacitation and I'm not entirely clear about how well defined some of these terms are. Rather than address these issues, I was hoping I could just consider what other people have written down and go with that. If anybody would be willing to share what they put down, that would be greatly appreciated.

Terminal condition is a condition that cannot be cured (of course), but the specific interpretation might vary depending on where you live, and who your doctors are, so you should make specific what you mean. A terminal condition could be an illness that can't be cured, like stage IV cancer, that you have, but is not imminently threatening your life - you could be in the hospital for an acute condition that is life threatening but is curable, and if treated aggressively you could continue to have a good quality of life until your cancer eventually kills you. More commonly though, a terminal condition is understood to be an imminently threatening condition (like having severe heart and renal failure that requires you to remain on IV medications in an ICU setting indefinitely in order to sustain your life), where treatment can prolong your life but it's inevitable that you will never be dischargeable from the hospital. If you develop an infection, antibiotics can cure the infection, but your underlying condition will remain. IV nutrition can sustain your life for some period longer than normal (because you're unable to eat), but puts you at high risks of disseminated infections that will then require more antibiotics to treat, producing antibiotic resistant bacteria and more severe infections in the future. In this situation, being placed on a ventilator will likely worsen your heart and lung function, to the point where once you get on, you won't get off.

A permanently unconscious condition is usually one where there is severe brain damage, both cortical and brainstem, to the point where in expert neurologists' opinion, you will never regain consciousness. A minimally conscious condition is one in which you are conscious, but at the very minimum definition of being conscious - ie being awake. To all testing, you are not really interacting in any meaningful way (think Terry Schiavo).

Overall, the best thing to do is to describe as much as you can in the "Instructions for health care proxy" section what your wishes are. It could be just saying that you want life-saving treatments if there is a reasonable chance (you can specifically define a percentage if you like) that you will regain consciousness to the point of being able to interact with friends/family in a meaningful way, or that you want life-saving treatment if there is a reasonable chance that you will recover enough to have a chance at spending at least 1-2 weeks outside the hospital to spend time with friends/family in a meaningful way, for example.